Polyethylene Films and Production of Such Films

ABSTRACT

A method of forming a finished film comprising extruding a molten polyethylene comprising a diene terpolymer modifier through a die opening to form a film, wherein the diene-terpolymer modifier is a terpolymer comprising ethylene-derived units, C 3  to C 10  α-olefin derived units, and diene-derived units; causing the film to progress in a direction away from the die opening; cooling the film at a distance from the die opening, the distance adjusted to allow relaxation of the molten polyethylene prior to solidification and/or crystallization upon cooling; and isolating a finished film therefrom. Desirably, the polyethylene is a linear low density polyethylene, and the die and cooling is suitable for forming a blown film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Ser. No. 62/004,278, filed May29, 2014 and EP 14175210.5 filed Jul. 1, 2014, each of which isincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to polyethylene films and the process usedto form such films, and in particular, an improved blown film processand the films that result therefrom.

BACKGROUND OF THE INVENTION

The blown film technique is an important means by which polyethylenefilms are manufactured. A major use of such films is in making bags,where the films can be formed as continuous cylinders then crimped toclose one end. The process to blow polyethylenes into such films howeveris complex, requiring a balance between processability (flowability andmelt strength) on the one hand and mechanical properties (e.g., TensileStrength, Modulus) on the other. Improvements in both the materials usedto make such films, and the process itself, can synergistically makeblown films a more attractive commercial process. The inventors herehave found desirable materials and methods of forming blown films.

Methods of cooling films extruded through a ring die have been discussedin U.S. Pat. No. 3,891,790. Other references of interest include: U.S.Pat. No. 7,687,580; U.S. Pat. No. 6,509,431; U.S. Pat. No. 6,355,757;U.S. Pat. No. 6,391,998; U.S. Pat. No. 6,417,281; U.S. Pat. No.6,300,451; U.S. Pat. No. 6,114,457; U.S. Pat. No. 6,734,265; U.S. Pat.No. 6,147,180; U.S. Pat. No. 6,870,010; and U.S. Pat. No. 5,670,595;U.S. Pat. No. 3,568,252; WO 2007/067307; WO 2002/085954; US 2008/179780;US 2007/0260016; EP 0 544 098 A; and Guzman, et al., 56(5) AIChEJournal, 1325-1333 (2010).

SUMMARY OF THE INVENTION

Disclosed herein in part is a method of forming a finished filmcomprising extruding a molten polyethylene comprising a diene terpolymermodifier through a die opening to form a film, wherein thediene-terpolymer modifier is a terpolymer comprising ethylene-derivedunits, C₃ to C₁₀ α-olefin derived units, and diene-derived units;causing the film to progress in a direction away from the die opening,preferably in the molten state, partially molten, or softened due tosome partial cooling; cooling the film at a distance from the dieopening, the distance adjusted to effect the properties of the film; andisolating a finished film therefrom.

Also disclosed is a polyethylene blown film having a MD Tensile Strengthof the finished film is within a range from 6000 psi (41 MPa) or 8000psi (55 MPa) to 16,000 psi (110 MPa) comprising (or consistingessentially of, or consisting of) a linear low density polyethylenehaving a density within the range from 0.850 g/cm³ to 0.930 g/cm³ andwithin the range from 0.10 wt % to 10 wt % of a diene-terpolymermodifier; wherein the diene terpolymer modifier comprises within a rangefrom 0.01 wt % to 10.0 wt % diene derived units, and 1.0 wt % to 20 wt %of C₄ to Co₁₀ α-olefin derived units based on the weight of the dieneterpolymer, wherein the diene-terpolymer modifier has: a g′_(vis) ofless than 0.90; an M_(w) within a range of from 70,000 g/mol to 300,000g/mol; an M_(w)/M_(n) within the range of from 3.0 to 12; and anM_(z)/M_(n) of greater than 14.0.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagrammatic depiction of a blown film process.

FIG. 1B is a non-limiting diagrammatic depiction of the inventiveprocess, wherein “H” is the distance between the cooling device and thedie.

FIG. 2 is a plot of the Elmendorf Tear (MD) as a function of the Hermanorientation function, % crystallinity (χ) (chi) and inter-lamellarspacing (Δ) (delta) of the blown films.

FIG. 3 is a plot of the 1% Secant Flexural Modulus as a function of theHerman orientation function and % crystallinity (χ) and inter-lamellarspacing (Δ) of the blown films.

FIG. 4 is a chart showing the crystal size of various blown polyethylenefilms at various conditions and compositions, where the y-axis is theinter-lamellar spacing.

FIG. 5 is a chart showing the inter-lamellar spacing of various blownpolyethylene films at various conditions and compositions.

DETAILED DESCRIPTION

The inventors have surprisingly found that the addition of a minoramount of a diene-terpolymer modifier (“DTP”) with a polyethylene,especially LLDPE, in combination with a film process with a means forcooling the forming film that provides some distance from the die fromwhich the film emanates, yields significant enhancement of a number ofthe finished film's properties and the rate at which it can be produced.In this film forming process, a cooling device such as an air ring, forexample, is elevated (moved a distance from the die) allowing for moreeffective cooling of the forming film. It is believed that this allowsthe polymer molecules to “relax” in the melt for a period of time afterthe melt exits the die, and thus providing the distance allows suchrelaxation prior to crystallization of the polyethylene. In the moltenor semi-molten state, the molten polymer is stretched in both the TD andMD directions after it reaches the cooling device (e.g., elevated airring). Then the film is subjected to effective cooling from, forexample, both a trip-lip air ring and internal bubble cooling, common inblown film processes. It is evidenced that this new process and DTPaddition provide a balanced MD-TD orientation; hence, the film exhibitsenhanced physical properties. Desirably, the combination of DTP andseparation between the cooling and the die also creates a desiredcrystal size and morphology, which result in the enhanced stiffness andexcellent optical property.

Process to Produce a Film

The invention can be described in any embodiment as a method of forminga finished film comprising extruding a molten polyethylene comprising adiene terpolymer modifier through a die opening to form a film, whereinthe diene-terpolymer modifier is a terpolymer comprisingethylene-derived units, C₃ to C₁₀ α-olefin derived units, anddiene-derived units; causing the film to progress in a direction awayfrom the die opening, preferably in the molten state, partially molten,or softened due to some partial cooling; cooling the molten polyethylenein the form of a film at a distance from the die opening, the distanceadjusted to effect the properties of the film (e.g., to allow relaxationof the molten polyethylene prior to solidification and/orcrystallization upon cooling); and isolating a finished film therefrom.

By “extruding” what is meant is that the polymer and/or polymer blend ifformed into a melt such as by heating and/or sheer forces and is forcedto blend with other polymers and/or components (e.g., the polyethyleneand the modifier) and is then forced out of a die in a desirable form orshape to effect the form or shape of the emanating polymer melt, such asin a film, most preferably a tubular film. Most any type of apparatuswill be appropriate to effect “extrusion” such as a single or twin-screwextruder, or other melt-blending device as is known in the art and thatcan be fitted with a suitable die.

By “at a distance from the die”, what is meant is that the “coolingdevice”, such as a cooling ring that blows air on the forming film, islocated at least 1 or 2 or 4 or 8 cm from the die (or other distance asdescribed herein) preferably measured from the top or outer edge of thedie to the base of the cooling device.

By “causing the film to progress”, what is meant is that the filmforming from the die opening from hardening polyethylene is pulled orpushed mechanically or by some other means such as by air pressure(negative or positive) away from the die to create a continuous finishedfilm.

In a typical process, a polyethylene melt is extruded through a die suchas an annular slit die, usually vertically, to form a thin walled tube.Cooling preferably in the form of air is introduced via a ring in thecenter of the die to blow up the tube like a balloon. Cooling could alsobe effectuated by other means, and the air may be nitrogen/oxygen orother gases or mixtures of gases or liquids. Mounted on top of the die,a high-speed air ring blows onto the hot film to cool it. In the presentinvention, the cooling occurs at some distance “H” (see FIG. 1B) fromthe die, which is at least 1 cm as defined above. The tube of film canthen continue upwards (see arrows in FIGS. 1A and 1B), continuallycooling, until it may pass through nip rolls where the tube is flattenedto create what is known as a “lay-flat” tube of film. This lay-flat orcollapsed tube can then be taken back down the extrusion “tower” viamore rollers. On higher output lines, the air inside the bubble is alsoexchanged. This is known as IBC (Internal Bubble Cooling).

In any case, the lay-flat film is then either kept as such or the edgesof the lay-flat are slit off to produce two flat film sheets and woundup onto reels. Articles such as bags can be made from such lay-flatfilms. In this regard, if kept as lay-flat, the tube of film is madeinto bags by sealing across the width of film and cutting or perforatingto make each bag. This is done either in line with the blown filmprocess or at a later stage.

Preferably, the expansion ratio between die and blown tube of film wouldbe 1.5 to 4 times the die diameter. The drawdown between the melt wallthickness and the cooled film thickness occurs in both radial andlongitudinal directions and is easily controlled by changing the volumeof air inside the bubble and by altering the haul off speed. This givesblown film a better balance of properties than traditional cast orextruded film which is drawn down along the extrusion direction only.

A typical prior art blown film process is described with reference toFIG. 1A, where the ingredients used to form the film are added in anydesirable form, preferably as granules, in hopper 1, which feeds thematerial to the extruder 3, where the materials are melt blended at adesirable temperature through shear forces and/or heating. The moltenmaterial is then fed, with or without filtering, to a die 5 which isalso heated to a desired temperature and then forced from the die in thedirection of the arrow in FIG. 1A. The cooling of the forming film takesplace via 7, preferably a device that blows air that is at least 10 or20° C. cooler than the surrounding air. The air preferably blows againstthe outside of the film, most preferably around the entire circumferenceformed by the film. There is also air blown internally that both coolsand blows the film up like a balloon. The film 9 starts to expand whereit eventually cools and crystallizes to form finished film 11.

The inventive process is described with reference to FIG. 1B, where theactual apparatus useful in such a process shares many of the features inFIG. 1A. Materials used to form the film is fed into the extruder 23 viahopper 21, where the materials are melt blended and transferred in themolten state to the die 25. Here, unlike in the prior art process, theforming film “B” is allowed to form in the direction of the arrow for atime and distance “H” until reaching the cooling device 27, againpreferably a device that blows air that is at least 10 or 20° C. coolerthan the surrounding air. The medium, such as air, around the formingfilm B may be heated or otherwise moderated so as to facilitaterelaxation of the film in its molten or softened state during the timespent in the H distance. The forming film B desirably spends from 0.5 or1 or 5 seconds to 10 or 20 seconds in the zone described by the distanceH in FIG. 1B. Preferably, the cooling air is at a temperature within therange from 5 or 10° C. to 15 or 20 or 25, or 30° C.; and preferably thesurrounding temperature in the area of the forming film 29 is within arange from 20 or 30° C. to 50 or 60° C. The film then expands and coolsin the region 29 as it is cooled by, for example, cooler air blowingfrom 27, where a finished film 31 is eventually isolated by variousmeans such as by rollers, nips, etc.

The “distance” can be any distance from the die, preferably measuredfrom the top or outer edge of the die to the base of the cooling device.The optimal distance is one that allows for adequate relaxation of themolten polyethylene before it crystallizes into the finished film. Inany embodiment, the distance is at least 1 or 2 or 4 or 8 cm from thedie; or within a range of from 1, or 2, or 4, or 8 cm to 50 cm, or 60cm, or 80 cm, or 3 meters. Stated another way, the distance can bedescribed as the ratio of H/D and is within a range from 0.05, or 0.1 or0.5 or 1 to 2 or 3 or 4 or 5, or 10, or 15, or 20, where the H is thedistance from die exit to the “cooling”, for example, a cooling ring,and D is the diameter of a die (H and D are the same units). The“cooling” is preferably provided by air blown around the film. Air mayalso be blown inside the film if the finished film is a tube, and mostpreferably there is air blown inside the film-tube. Such air willemanate from the center of the die, near or at the die opening, and willmaintain the temperature in the vicinity “H” described above.

Preferably, the die used in the formation of the films herein isdesigned such that the die opening, through which the moltenpolyethylene emanates, is in the form of a ring and the moltenpolyethylene emanating therefrom is in the form of a continuous tube.The “Maximum Die Rate” is a normalized extrusion rate by die size whichis commonly used in blow film industry. The Maximum Die Rate as usedherein is expressed as following: Maximum Die Rate [lb/in-hr]=ExtrusionRate [lb/hr]/Die Circumference [inch]. Another definition of the MaximumDie Rate is expressed as following: Maximum Die Rate[kg/mm-hr]=Extrusion Rate [kg/hr]/Die Diameter [mm]. The Maximum DieRate at which the film is formed is at least 13, or 15, or 18 lb/in-hr(0.73, or 0.84, or 1.01 kg/mm-hr), or within a range from 13, or 15, or18, or 22 lb/in-hr to 26 or 30 or 40 lb/in-hr (0.73, or 0.84, or 1.01,or 1.23 kg/mm-hr to 1.46 or 1.69 or 2.25 kg/mm-hr); and preferably theMaximum Rate of extrusion is within a range from 350 lb/hr (159 kg/hr)to 500 lb/hr (227 kg/hr). Note that for the “Maximum Die Rate” in theEnglish unit, the die dimension is the die circumference, while inmetric unit, the die dimension is the die diameter.

Polyethylene Blend

The inventive method in any embodiment includes the extrusion of amolten composition which is a polyethylene blend comprising at least onepolyethylene and at least one DTP. The “polyethylene” that is useful inmaking films is preferably any type of homo- or co-polymer derived fromethylene and C₃ to C₁₀ α-olefins. Preferably, the polyethylene is alinear low density polyethylene having a density within the range from0.850 or 0.900 or 0.905 g/cm³ to 0.915 or 0.925 or 0.930 g/cm³. Also thelinear low density polyethylene preferably has a melt index (ASTM D 1238190° C., 2.16 kg) within the range from 0.20 or 0.40 or 0.60 or 0.80g/10 min to 1.20 or 1.40 or 1.60 or 2.00 or 4.00, or 8.0, or 10.0 g/10min.

Preferably, the polyethylene comprises within the range from 0.10 or0.50 wt % to 2.0 or 3.0 or 6.0 or 10 wt % of a diene-terpolymer (DTP)modifier. The diene-terpolymer modifier is a terpolymer comprisingethylene-derived units, C₃ to C₁₀ α-olefin derived units, anddiene-derived units; wherein the diene is preferably an alpha-omegalinear diene. Preferably, the diene terpolymer comprises within a rangefrom 0.01 wt % to 10.0 wt % diene derived units, and 1.0 wt % to 20 wt %of C₄ to C₁₀ α-olefin derived units based on the weight of the dieneterpolymer, wherein the diene terpolymer has a g′_(vis) of less than0.90; an M_(w) within a range of from 70,000 g/mol to 300,000 g/mol; anM_(w)/M_(n) within the range of from 3.5 to 12; and an M_(z)/M_(n) ofgreater than 7.0.

The DTP modifier can be described by a number of features andproperties. It primarily is comprised of ethylene-derived units, butwill also comprise within the range from 1.0 or 2.0 or 5.0 wt % to 12 or16 or 20 wt % of a C₄ to C₁₀ α-olefin derived units based on the weightof the DTP modifier, most preferably 1-butene, 1-hexene or 1-octene. TheDTP modifier also comprises within the range from 0.01 or 0.05 or 1.0 wt% to 5.0 or 8.0 or 10.0 wt % diene derived units, preferably alpha-omegadienes, based on the weight of the DTP modifier. The remainder of theDTP is comprised of ethylene-derived units. The dienes may preferably beselected from the group consisting of 1,4-pentadiene, 1,5-hexadiene,1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene,1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, and1,13-tetradecadiene, tetrahydroindene, norbornadiene also known asbicyclo-(2.2.1)-hepta-2,5-diene, dicyclopentadiene,5-vinyl-2-norbornene, 1,4-cyclohexadiene, 1,5-cyclooctadiene,1,7-cyclododecadiene derived units, and combinations thereof. Morepreferably, the diene is selected from 5-vinyl-2-norbornene,1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene,1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene,1,12-tridecadiene, and 1,13-tetradecadiene derived units; and mostpreferably selected from 1,7-octadiene and 1,9-decadiene derived units.The DTP modifier preferably has a density within the range of from 0.890or 0.905 or 0.910 or 0.915 g/cm³ to 0.920 or 0.925 g/cm³.

The properties of the DTP modifier can of course vary depending on theexact process used to make it, but preferably the DTP modifier has thefollowing measurable features. Certain GPC (Light Scattering (LS) orDifferential Refractive Index (DRI)) measurable features include thefollowing: The weight average molecular weight (Mw) is preferably withina range of from 70,000 or 80,000 or 100,000 g/mol to 140,000 or 160,000or 180,000 or 200,000 or 300,000 g/mol. The number average molecularweight (Mn) is preferably within a range of from 15,000 or 20,000 or30,000 g/mol to 35,000 or 40,000 or 50,000 or 80,000 g/mol. Thez-average molecular weight (Mz) is preferably greater than 400,000 or500,000 or 800,000 g/mol, and more preferably within a range of from300,000 or 400,000 or 500,000 or 800,000 g/mol to 1,000,000 or 1,200,000or 1,500,000 or 2,000,000 g/mol. Finally, the DTP modifier has amolecular weight distribution (Mw/Mn) within the range of from 3.0 or3.2 to 6.0 or 7.0 or 8.0 or 10.0 or 12.0; and an Mz/Mn value of greaterthan 14 or 16 or 18 or 20, or within a range of from 14 or 16 or 18 to24 or 28 or 30 or 36. For the GPC data, DRI (differential refractiveindex) method is preferred for Mn, while LS (light scattering) ispreferred for Mw and Mz.

Certain DSC measurable properties include the following: The DTPmodifier preferably has a melting point temperature (T_(m)) within therange of from 90 or 95 or 100 or 110° C. to 115 or 125 or 130° C. TheDTP modifier also preferably has a crystallization temperature (T_(c))within the range of from 75 or 80 or 85 or 90° C. to 110 or 115 or 120or 125° C. The DTP modifier also preferably has a heat of fusion (H_(f))within the range of from 70 or 75 or 80 J/g to 90 or 95 or 100 or 110 or120 or 130 or 140 J/g.

Certain melt flow properties of the DTP modifier include the following:The DTP modifier preferably has a melt index (190° C./2.16 kg, “I₂”) of15 g/10 min or less, 10 g/10 min or less, 5 g/10 min or less or 2 g/10min or less, or more preferably within the range of from 0.10 or 0.20 or0.30 or 0.80 or 1.0 g/10 min to 4 or 5 or 6 or 8 g/10 min. The DTPmodifier has a wide ranging high load melt index (I₂₁), but preferablyhas a high load melt index (190° C./21.6 kg, “I₂₁”) within the range offrom 0.10 or 0.20 or 0.30 or 0.80 or 1.0 g/10 min to 4 or 5 or 6 or 8 or20 or 40 or 60 or 80 or 100 or 140 or 180 or 200 g/10 min. The DTPmodifier has a melt index ratio (I₂₁/I₂) within a range of from 20 or 25or 30 to 70 or 75 or 80 or 85 or 90.

Certain dynamic properties of the DTP modifier include the following:The DTP modifier preferably has a Complex Viscosity at 0.1 rad/sec and atemperature of 190° C. within the range of from 20,000, or 50,000, or100,000, or 150,000, Pa*s to 300,000, or 350,000, or 400,000, or 450,000Pa*s. The DTP modifier preferably has a Complex Viscosity at 100 rad/secand a temperature of 190° C. within the range of from 500 or 700 Pa*s to5,000 or 8,000 or 10,000 or 15,000 Pa*s. Also, the DTP modifierpreferably has a Phase Angle at the Complex Modulus of 10,000 Pa withinthe range of from 10 or 15 or 20 or 250 to 45 or 50 or 55 or 600 whenthe complex shear rheology is measured at a temperature of 190° C. TheDTP modifier preferably has a Phase Angle at the Complex Modulus of100,000 Pa within the range of from 10 or 150 to 25 or 35 or 450 whenthe complex shear rheology is measured at a temperature of 190° C.

Finally, the DTP modifier has a level of branching indicated by themeasured value of the branching index “g′_(vis)”. The value for g′_(vis)is preferably less than 0.90 or 0.80 or 0.75 or 0.60, or within a rangeof from 0.30 or 0.40 or 0.60 to 0.70 or 0.90. A polyethylene is “linear”when the polyethylene has no long chain branches, typically having ag′_(vis) of 0.97 or above, preferably 0.98 or above. “Linearpolyethylenes” preferably include ethylene polymers having a g′_(vis) of0.95 or 0.97 or more, and as further described herein. Thus, a lowervalue for g′_(vis) indicates more branching. The methods for measuringg′_(vis) are described in U.S. Ser. No. 13/851,769 filed Mar. 27, 2013;U.S. Ser. No. 13/851,752 filed Mar. 27, 2013; U.S. Ser. No. 13/800,098,filed Mar. 13, 2013; and U.S. Ser. No. 13/623,242, filed Sep. 20, 2012.

Finished Film

The improvement resulting from the process can be seen in the lamellarstructure of the inventive films. This is reflected in SAXS/WAXS dataacquired on the finished, blown films. This technique yields informationpertaining to the crystal structure of the materials. This can bequantified in the following relationship(s), wherein the films ETMD andSCMD are defined as follows:

ETMD+0.10³ f _(H)·χΔ>200 (g/mil); or

ETMD+0.103f _(H)·χΔ>240 (g/mil); or

ETMD+0.103f _(H)·χΔ>280 (g/mil);

-   -   either separate from, or in conjunction with the following        relationships

SCMD−2.62f _(H)·χΔ>21,000 (psi); or

SCMD−2.62f _(H)·χΔ>22,000 (psi); or

SCMD−2.62f _(H)·χΔ>23,000 (psi);

wherein “ETMD” is MD Elmendorf tear (g/mil); SCMD is the MD 1% Secant(psi); f_(H) is the Herman Orientation Function (lamella); χ is percentcrystallinity (%); and Δ is inter-lamellar spacing (Å). Ideally, theinventive process is such that the properties of the forming film can beadjusted by the amount of modifier added to the polyethylene and/or theamount of cooling, such as by adjusting the distance of the coolingdevice from the die. Such changes will influence these relationships,and are depicted graphically in FIGS. 2 and 3. As an example, theinter-lamellar spacing (Δ) of the film may be effected by suchadjustments.

Desirably, the % crystallinity (χ) or inter-lamellar spacing (Δ) of theforming film could be measured as described below, and this could beused to aid in adjusting the distance of the cooling and the amount of“relaxation” or crystallization of the forming film. For instance, thedistance could be adjusted to keep % crystallinity (χ) of the film inthe vicinity of “H” below 50% or 40% or 30% or 20% or 10%, or between 1or 5 or 10% to 15 or 20 or 30% crystallinity.

Finished films formed from the polyethylene, preferably a LLDPEincluding the DTP, have many desirable properties. Preferably, the MDTensile Strength of the finished film is greater than 6000 or 8000 or9000 psi, or within a range from 6000 psi (41 MPa) or 8000 psi (55 MPa)to 16,000 psi (110 MPa). The finished films preferably have a MDElongation of greater than 480 or 490 or 500 or 550%, or within a rangefrom 480% to 680%. The Haze (ASTM D1003) of the finished film ispreferably less than 6 or 4%. Also, in any embodiment the 1% AverageSecant Flexural Modulus (“Flex Mod”) of the inventive film is within arange from 25,000 (172), or 28,000 psi (193 MPa) to 35,000 (241), or40,000 psi (276 MPa) in either the MD or TD; and in any embodiment theDart Impact is within a range from 400, or 420 g/mil to 500, or 550, or600, or 650, or 700, or 800, or 900, or 1000 g/mil. Desirably, thefinished film has a thickness within the range from 10 or 15 μm to 50 or75 or 100 or 150 μm.

As mentioned, the finished films have many desirable end uses such asbags and packaging material. The finished films are most preferably“blown films” as is commonly referred to in the art, being cylindricalacross its axis, and continuous perpendicular to this axis. The finishedfilms are typically collected and formed into rolls and can bemanipulated further by sealing one end and/or cut to form individualarticles such as bags.

The improved properties of the films also exist in the unfinishedpolymer melt that forms the film. Such improvements allow faster linespeeds thus debottlenecking of blown film processes. The maximum rate ofproduction, measured for instance as the Maximum Die Rate, at which thefilm can be produced is controlled in part by the “bubble stability” ofthe forming film. When the line speed/extrusion rate is over the maximumrate, the bubble formed by the film being blown by air becomes unstable.The bubble stability is related two main factors:

-   -   1. Melt strength of the polymer blend: higher the melt strength,        higher the maximum rate. The addition of small amount of the        diene terpolymer (DTP) enhances the melt strength of the base        polyethylene significantly. It has been found that the        polyethylene blends with DTP have higher maximum rate than the        polyethylenes.    -   2. Cooling capability of the line: higher cooling capability,        higher the maximum rate. It has been found that the ability to        move the cooling device for the forming film “downstream” of the        die improves its properties and allows faster rates of        production.

Typically, the Maximum Die Rate is used to normalize the extrusion rate.For a traditional blown film line having a fixed cooling device at thedie, the Maximum Die Rate even using the DTP is about 13 to 13.5lb/in-hr. But when the inventive process is used, these same blends canbe formed at a Maximum Die Rate of at least 18, or 20, or 22 lbs/in-hr.

Thus, in a preferred embodiment, the inventive process results in aninventive polyethylene blown film having a MD Tensile Strength within arange from 6000 psi (41 MPa) or 8000 psi (55 MPa) to 16,000 psi (110MPa) comprising (or consisting essentially of) a linear low densitypolyethylene having a density within the range from 0.850 g/cm³ to 0.930g/cm³ and within the range from 0.10 wt % to 10 wt % of adiene-terpolymer modifier; wherein the diene terpolymer modifiercomprises ethylene-derived units and within a range from 0.01 wt % to10.0 wt % diene derived units, and 1.0 wt % to 20 wt % of C₄ to C₁₀α-olefin derived units based on the weight of the diene terpolymer,wherein the diene terpolymer has: a) a g′_(vis) of less than 0.90; b) anM_(w) within a range of from 70,000 g/mol to 300,000 g/mol; c) anM_(w)/Mn within the range of from 3.0 to 12; and d) an M_(z)/M_(n) ofgreater than 14.0. The DTP and LLDPE may have other features asdescribed herein.

The various descriptive elements and numerical ranges disclosed hereinfor the inventive film forming process and the inventive films can becombined with other descriptive elements and numerical ranges todescribe the invention(s); further, for a given element, any uppernumerical limit can be combined with any lower numerical limit describedherein, including the examples in jurisdiction which allow such ranges.The features of the invention are demonstrated in the followingnon-limiting examples.

Examples Test Methods

All test methods are well known in the art and published in US2013-0090433 A1. The crystallization and melting point temperatures weredetermined by Differential Scanning Calorimetry at 10° C./min. The highload melt flow (I₂₁ or HLMI) parameters are determined per ASTM D 1238190° C., 21.6 kg. Polymer molecular weight (weight-average molecularweight, Mw, number-average molecular weight, Mn, and z-averagedmolecular weight, Mz) and molecular weight distribution (Mw/Mn) aredetermined using Size-Exclusion Chromatography. Equipment consists of aHigh Temperature Size Exclusion Chromatograph (either from WatersCorporation or Polymer Laboratories), with a differential refractiveindex detector (DRI), an online light scattering detector, and aviscometer (SEC-DRI-LS-VIS). For purposes of the claims, SEC-DRI-LS-VISshall be used. Three Polymer Laboratories PLgel 10 mm Mixed-B columnsare used. The nominal flow rate is 0.5 cm³/min and the nominal injectionvolume is 300 μL. The various transfer lines, columns and differentialrefractometer (the DRI detector) are contained in an oven maintained at135° C. Solvent for the SEC experiment is prepared by dissolving 6 gramsof butylated hydroxy toluene as an antioxidant in 4 liters of reagentgrade 1,2,4-trichlorobenzene (TCB). The TCB mixture is then filteredthrough a 0.7 μm glass pre-filter and subsequently through a 0.1 μmTeflon filter. The TCB is then degassed with an online degasser beforeentering the SEC.

For ethylene copolymers with alpha-omega-dienes, propylene and C4 to C10α-olefins, the presence of long chain branched structures in the dieneterpolymers can be detected using nuclear magnetic resonancespectroscopy (NMR). In ¹³C-NMR the modifiers are dissolved intetrachloroethane-d2 at 140° C. and the spectra are collected at 125° C.Assignments of peaks for ethylene/propylene, ethylene/butene,ethylene/hexene, and ethylene/octene copolymers have been reviewed byJames C. Randall in 29(2) Polymer Reviews, 201-317 (1989). Assignmentsfor propylene/butene, propylene/pentene, propylene/hexene,propylene/heptene, and propylene/octene are presented by U. M Wahner, etal., (204 Macromol. Chem. Phys. 1738-1748 (2003)). These assignmentswere made using hexamethyldisiloxane as the internal standard. Toconvert them to the same standard used in the other references, add 2.0to the chemical shifts. Assignments and a method of measuring deceneconcentration have been reported for propylene/ethylene/deceneterpolymers in Escher, Galland, and Ferreira (41 J. Poly. Sci., Part A:Poly. Chem., 2531-2541 (2003)) and Ferreira, Galland, Damiani, andVillar (39 J. Poly. Sci, Part A: Poly. Chem., 2005-2018 (2001)). Thepeaks in the ¹³C-NMR spectrum of ethylene/norbornadiene copolymers areassigned by Mönkkönen and Pakkanen (200 Macromol. Chem. Phys., 2623-2628(1999)) and Radhakrishnan and Sivaram (200 Macromol. Chem. Phys.,858-862 (1999)). More details are disclosed in US 2013-0090433 A1.

X-Ray Test Methods

Each set of polymer films was analyzed using Small- and Wide-Angle X-rayScattering (SAXS/WAXS) techniques. The X-ray source was a rotating anodeusing a Copper target (wavelength=0.154 nm) and a Rigaku SMAX 3000system. The film was placed in a sample holder at room temperature andthe SAXS and WAXS data were collected simultaneously. The SAXS data werecollected using a 2D CCD camera which was placed 1.127 m from thesample. The WAXS data were collected using an image plate with a hole inthe center (allowing for the scattered X-rays at smaller angles to passthrough) and this was placed 0.071 m from the sample.

The 2D X-ray patterns showed that all materials had an inherent degreeof molecular orientation: both in the small scale crystal (obtained fromWAXS) and in the larger range order which describes how these crystalsconnect via amorphous non-crystalline chains (obtained from SAXS). Themolecular orientation is observed by an anisotropic pattern: thescattering rings are not uniform in intensity; indicative of moremolecules being oriented in one specific direction, in our case, thisdirection is the machine direction (MD). The quantification of thisorientation is done by calculating at which angle the greatest intensitylies and to what extent. These angles are then used to compute theHermans Orientation Function (f_(H)). The f_(H) can be computed for bothSAXS and WAXS data, f_(H) from SAXS data describes the ordering in thecrystal stacks, or lamellae, connected by amorphous polymer chains.f_(H) from WAXS describes the order of the individual crystalliteswithin the lamellae. A f_(H) value of zero indicates anisotropy (noorder), a value of one (1) indicates perfect parallel alignment to MD,and a value of −0.5 indicates perfect perpendicular alignment to MD. ForPE blown film cases positive fractional values of a f_(H) are obtained,indicating preferential alignment to MD, but not perfect alignment.

The extent of crystallinity (or “relaxation”), or amount of polymerchain that crystallized, can also be calculated from the WAXS data. The2D images are collapsed to an Intensity versus Angle profile and the twosharp peaks observed for PE are fitted to a Guassian function and theareas are calculated. The ratio of these peak areas to the total areaunder the scattering profile yields the extent of crystallinity. Thefull width at half maximum of these crystalline peaks (FWHM), β (beta),can be used to calculate the crystallite size, r (tau), using theScherrer equation:

$\tau = \frac{\kappa\lambda}{\beta \mspace{14mu} \cos \mspace{14mu} \theta}$

where λ (lambda) is the wavelength of the X-rays and θ (theta) is thescattering angle.

The inter-crystalline (or lamellae) spacing can also be calculated fromSAXS from the peak maximum once the 2D SAXS data are collapsed to a 1Dintensity versus Angle profile.

1% Average Secant Flexural Modulus (ASC, or “Secant Flexural Modulus”,or “Flex Mod”), is measured as specified by ASTM D-882.

Dart F50, or Dart Drop Impact or Dart Impact (DI), reported in grams (g)and/or grams per mil (g/μm), is measured as specified by ASTM D-1709,method B, using a dart with a phenolic composite head.

Example DTPs

Diene-terpolymer modifiers (DTP) (examples: DTP (1,7), DTP2, DTP3, andDTP (1,9)) were made in a continuous stirred-tank reactor operated in asolution process. The reactor was a 1.0-liter stainless steel autoclavereactor and was equipped with a stirrer, a water cooling/steam heatingelement with a temperature controller and a pressure controller.Solvents and monomers (e.g., ethylene, hexene and/or octene) were firstpurified by passing through columns of alumina and molecular sieves. Thepurified solvents and monomers were then chilled to below 4° C. bypassing through a chiller before being fed into the reactor through amanifold. Ethylene was delivered as a gas solubilized in the chilledsolvent/monomer mixture. Solvent and monomers were mixed in the manifoldand fed into the reactor through a single port. All liquid flow rateswere controlled and measured using Brooksfield mass flow controllers.1,7-octadiene and 1,9-decediene were purified and then diluted withisohexane and fed into the reactor using a metering pump.

Rac-dimethylsilylbis(indenyl)zirconium dimethyl was pre-activated withN,N-dimethyl anilinium tetrakis (heptafluoro-2-naphthyl) borate at amolar ratio of about 1:1 in toluene. The pre-activated catalyst solutionwas kept in an inert atmosphere and was fed into the reactor using ISCOsyringe pump through a separated line. Catalyst and monomer contactstook place in the reactor.

As an impurity scavenger, 200 ml of tri-n-octyl aluminum (TNOA) (25 wt %in hexane, Sigma Aldrich) was diluted in 22.83 kilogram of isohexane.The TNOA solution was stored in a 37.9-liter cylinder under nitrogenblanket. The solution was used for all polymerization runs until about90% of consumption, and then a new batch was prepared. The feed rates ofthe TNOA solution were adjusted in a range from 0 (no scavenger) to 4 mlper minute to optimize catalyst activity.

The reactor was first prepared by continuously N₂ purging at a maximumallowed temperature, then pumping isohexane and scavenger solutionthrough the reactor system for at least one hour. Monomers and catalystsolutions were then fed into the reactor for polymerization. Once theactivity was established and the system reached equilibrium, the reactorwas lined out by continuing operation of the system under theestablished condition for a time period of at least four times of meanresidence time prior to sample collection. The reactor effluent,containing mostly solvent, polymer and unreacted monomers, exited thereactor through a pressure control valve that reduced the pressure toatmospheric. This caused most of the unconverted monomers in thesolution to flash into a vapor phase which was vented from the top of asample collecting box. The liquid phase, comprising mainly polymer andsolvent, was collected for polymer recovery. The collected samples werefirst air-dried in a hood to evaporate most of the solvent, and thendried in a vacuum oven at a temperature of about 90° C. for about 12hours. The vacuum oven dried samples were weighed to obtain yields. Allthe reactions were carried out at a pressure of about 350 psig. Thepolymerization process condition and some characterization data arelisted in Table 1. For each polymerization run, the catalyst feed rateand scavenger fed rate were adjusted to achieve a desired conversionlisted in Table 1.

TABLE 1 Synthesis Summary of DTPs Example Number DTP(1,9) DTP2 DTP3DTP(1,7) Polymerization temperature (° C.) 130 130 130 130 Ethylene feedrate (slpm) 8 8 8 8 Comonomer 1-octene 1-hexene 1-hexene 1-hexeneComonomer feed rate (g/min) 1.8 1.8 1.8 1.8 α,ω-diene 1,9-decadiene1,9-decadiene 1,9-decadiene 1,7-octadiene α,ω-diene feed rate (ml/min)0.024 0.029 0.029 0.049 Isohexane feed rate (g/min) 55.2 57 64.7 55.2Polymer made (gram) 2198 2553.5 1443 4793 Conversion (%) 84.4% 87.2%88.7% 88.7% Ethylene content (wt %) 90.9 88.7 89.7 88.9 Tc (° C.) 97.788.0 91.3 87.7 Tm (° C.) 114.3 108.5 108.3 106.6 Heat of fusion (J/g)125.9 116.7 118.7 113.3 Mn DRI (g/mol) 34,573 31,951 32,372 35,720 MwDRI (g/mol) 172,198 153,460 155,123 128,735 Mz DRI (g/mol) 587,828514,216 594,848 418,163 Mn LS (g/mol) 58,716 45,814 41,495 40,400 Mw LS(g/mol) 277,712 236,287 203,845 157,907 Mz LS (g/mol) 1,453,6271,175,659 999,196 717,895 g′_(vis) 0.568 0.601 0.634 0.735 I₂₁ (gram/10min) 0.13 0.99 1.22 2.24 Complex shear viscosity at 0.1 rad/s (Pa s)311,000 189,000 172,000 117,000 Complex shear viscosity at 100 rad/s (Pas) 1,743 1,545 1,469 1,293 Phase angle at G* = 100,000 Pa (degree) 21.025.1 24.9 27.5

Film Compositions

64% DTP2 and 36% DTP3 were first mixed together and used as a modifierto improve film properties of mLLDPE. The mixture is referred as to as“DTP2-(1,9)” in this disclosure. Exceed™ Polyethylene 1018 (“Exceed1018”) is an mLLDPE (metallocene ethylene/hexene copolymer) availablefrom ExxonMobil Chemical Company (Houston, Tex.), having an MI of 1.0dg/min and a density of 0.918 g/cm³. Polyethylene LD071.LR™ (alsoreferred to as LDPE or LD071) is an LDPE available from ExxonMobilChemical Company (Houston, Tex.) having an MI of 0.70 dg/min and adensity of 0.924 g/cm³. Enable™ 2005 polyethylene (also referred asEnable 2005 or “EN2005”) is a metallocene ethylene-hexene copolymerhaving a melt index of 0.5 dg/min (ASTM D 1238, 2.16 kg, 190° C.) anddensity of 0.920 g/cm³.

Compounding

The various DTPs were used as modifier to mLLDPE to improve the filmblowing process and film properties. In each case, the chosen DTP wasground in a Wiley mill mixer and homogenized with an antioxidant packagein a 1 inch Haake twin screw extruder. An antioxidant package wasincluded that consisted of 15 wt % Irganox 1076™, 61 wt % Weston 399™and 24 wt % of FX592DA™. A blend composition was compounded with 1 wt %of DTP (by weight of the combined ingredients) produced in the examplesdescribed with Exceed™ 1018. The blends were prepared in a Coperion™ ZSK57 mm twin screw extruder. Likewise, 5 wt % LDPE and 10 wt % Enable™2005 blends with Exceed 1018 were also prepared in the Coperion ZSK57 mmtwin screw extruder for comparison.

Inventive Blown Film Process

The blown films were produced on a blown film line (Line I) having a 160mm mono-layer die setting with a 90 mm grooved feed extruder. Theadjustable air ring had a triple air lips and there is IBC (internalbubble cooling). It had 1 mil film, 2.5 blow-up ratio (BUR), 60 mil diegap and 14 inch (355 mm) air ring height “H”. The blown film conditionsand equipment setting are detailed in Table 2, where the air ring airtemperature was 12° C., the surrounding temperature was 25-30° C.

TABLE 2 Representative Process Data for Inventive films produced on LineI Equipment Condition Units Value Gauge (measured by lab) Mil 0.98 Gauge2σ % 4.6 BUR 2.5 Lay Flat In 24.8 Total Extrusion Rate lbs/hr 196.4Maximum Die Rate lbs/hr-in  9.9 to 20.0 Frost Line Height in (mm) 30(762) Line Speed (primary nip) Fpm 168.3 Extruder Speed Rpm 33.5Extruder Load % 53.3 Specific Output lb/hr/rpm 5.86 Air Ring Height in(mm) 14 (355) Feed Throat Temperature ° C. 23.8 Barrel Temperatures(1-6) ° C. 179 to 188 Die Temperature ° C. 204 Melt Temperature (¾″ in)° C. 214 Melt Temperature (average) ° C. 212 Melt Temperature at lastbarrel ° C. 210 Melt Pressure at last barrel Psi 4,816 Air Ring Speed %28.5 IBC Supply Speed % 38 IBC Exhaust Speed % 41 Air Ring Air Temp ° C.12 IBC Air Temp ° C. 33 Exhaust air Temp ° C. 44

TABLE 3 Inventive Film 1-5 Properties at various Maximum Die RatesParameter 1 2 3 4 5 Film Identity Exceed 1018 Exceed 1018 5 wt % 5 wt %10 wt % LD071 + LD071 + Enable 2005 + Exceed 1018 Exceed 1018 Exceed1018 Maximum Die Rate (lb/hr-in) 9.9 18.0 10.0 20.0 10.1 Frost LineHeight (in) 30 51 28 44 28 Gauge Mic (mils) Average 0.99 1 0.98 0.991.03 Low 0.92 0.95 0.91 0.94 0.95 High 1.1 1.05 1.09 1.06 1.11 1% FlexMod (psi) MD 25,634 26,605 26,137 30,070 26,096 TD 28,427 31,005 28,76834,448 28,392 Tensile Yield Strength (psi) MD 1,397 1,462 1,344 1,4491,359 TD 1,312 1,372 1,433 1,505 1,396 Elongation @ Yield (%) MD 6.9 86.2 6.1 6 TD 5.9 5.4 6.3 5.7 8 Tensile Strength (psi) MD 8,363 8,4477,685 8,350 10,571 TD 6,914 7,350 7,748 7,359 8,916 Elongation @ Break(%) MD 492 508 483 525 537 TD 589 655 604 656 629 Elmendorf Tear MD (g)243 290 199 153 232 TD (g) 370 412 496 554 448 MD (g/mil) 246 284 199153 232 TD (g/mil) 374 420 481 548 440 Haze (%) 6.4 11.9 2.5 3 3 Gloss(GU) MD 63 53 84 82 78 TD 66 55 85 83 80 Dart Impact, Composite Method A(g) 876 687 765 555 885 (g/mil) 885 687 781 561 859 Puncture, BTECMethod B Peak Force (lbs) 12.8 13.3 11.8 11.6 14.9 Peak Force (lbs/mil)12.9 13.3 12.1 11.7 14.5 Break Energy (in-lbs) 44.7 47.2 30.9 31.8 50.3Break Energy (in-lbs/mil) 45.2 47.2 31.6 32.1 48.8

TABLE 4 Inventive Films 6-10 Properties at various Maximum Die RateParameter 6 7 8 9 10 Film Identity 10 wt % 1 wt % 1 wt % 1 wt % 1 wt %Enable 2005 + DTP (1,7) + DTP (1,7) + DTP2- (1,9) + DTP2- (1,9) + Exceed1018HA Exceed 1018HA Exceed 1018HA Exceed 1018HA Exceed 1018HA Max DieRate (lb/hr-in) 20.0 10.0 20.0 10.0 20.0 Frost Line Height (in) 55 28 6228 51 Gauge Mic (mils) Average 1.08 0.99 1.03 1.02 1.06 Low 1.03 0.920.95 0.9 0.95 High 1.12 1.07 1.1 1.11 1.14 1% Flex Mod (psi) MD 28,47225,823 28,925 26,986 29,892 TD 32,079 28,710 33,660 28,588 34,124Tensile Yield Strength (psi) MD 1,389 1,338 1,434 1,360 1,457 TD 1,3791,363 1,420 1,410 1,506 Elongation @ Yield (%) MD 6 6.6 6.4 6.1 6.4 TD5.2 6.1 6.5 6.3 5.6 Tensile Strength (psi) MD 9,660 10,735 9,777 7,7426,853 TD 8,235 9,224 8,094 7,885 7,558 Elongation @ Break (%) MD 550 538525 472 488 TD 685 630 645 590 637 Elmendorf Tear MD (g) 267 206 228 199219 TD (g) 521 396 423 394 455 MD (g/mil) 243 206 215 191 201 TD (g/mil)501 385 423 382 434 Haze (%) 6.2 1.8 4 1.7 3.3 Gloss (GU) MD 68 87 77 8879 TD 73 89 78 89 82 Dart Impact, Composite Method A (g) 639 1071 8361011 821 (g/mil) 592 1082 811 991 774 Puncture, BTEC Method B Peak Force(lbs) 14 14.4 14.6 15 15.2 Peak Force (lbs/mil) 13 14.6 14.1 14.7 14.3Break Energy (in-lbs) 47 49.6 51.5 52.5 53.7 Break Energy (in-lbs/mil)43.5 50.1 50 51.5 50.7

Comparative Blown Film Process

Blown films of blends of LLDPE (Exceed™ 1018) and DTP(1,9) as well as ablend of LLDPE (Exceed 1018) and LD071 were prepared as comparativeexamples for blown film process. The comparative examples were achievedin a blown film line with a traditional fixed cooling ring against thedie (blown film Line II) so that “H” is zero, which has a 2.5″ extruderof L/D of 30:1. Line II was equipped with a 6″ mono-layer die and duallip air ring. The die was able to rotate to provide a more uniform meltdistribution. During the process, the bubble passed through a bubblecage to be stabilized. Then bubble to be flattened into a sheet afterpassing a collapsing frame. Then the sheet travels through primary nipand secondary nip which control and provide the desired film tension,line speed and gauge at a given extrusion rate. Then the sheet was woundinto a roll in a film winder. Process conditions are summarized in Table5, and the results of the film production outlined in Table 6.

TABLE 5 Representative Process Data for Comparative films produced onLine II Equipment Condition Units Value Horse Power HP 21.7 ExtruderMelt Temperature ° C. 207 Extruder Pressure psi 4,200 BUR 2.5 ExtruderMotor Load % 66.6 Extruder RPM rpm 61.5 Line Speed ft/min 167 ExtrusionRate lb/hr 188 Frost Line Height in (mm) 19-24 (483-586) Maximum DieRate lb/hr-in 10.0-13.0 Maximum Line Speed ft/min 201 Maximum ExtrusionRate lb/hr 226 Maximum Line Speed % 120% Maximum Line Speed Increase % 20%

TABLE 6 Comparative Film Properties Sample C1 C2 C3 C4 C5 C6 FilmIdentity Exceed 1018 5 wt % Exceed 1018 Exceed 1018 1 wt % 2 wt %LD071 + DTP(1,9) + DTP(1,9) + Exceed 1018 Exceed 1018 Exceed 1018Maximum Die Rate (lb/hr-in) 12.0 12.5 11.0 12.9 13.0 12.8 1% Flex Mod(psi) MD 24,049 28,503 25,842 27,395 29,007 34,072 TD 28,506 35,31729,355 30,765 37,376 43,555 Tensile Yield Strength (psi) MD 1,361 1,4211,303 1,341 1,410 1,592 Elongation @ Yield (%) MD 7.1 6.1 6.4 6.1 6.36.3 TD 6.6 7.2 7.3 6.3 7.6 6.4 Tensile Strength (psi) MD 9,473 9,5727,428 7,989 9,153 10,168 TD 8,308 8,052 6,661 6,624 7,806 7,358Elongation @ Break (%) MD 512 521 468 465 457 422 TD 665 662 610 610 664628 Elmendorf Tear MD (g) 256 138 238 226 292 87 TD (g) 430 522 405 418466 499 MD (g/mil) 250 136 243 226 292 89 TD (g/mil) 430 522 405 423 466509 Haze (%) 16.5 2.4 12.8 8.5 3.2 1.9 Dart Impact/Composite Dart Head -Method A (g/mil) 911 647 921 821 871 524 Puncture, ASTM Probe A MaximumForce (lbs) 8 9 — — — — Maximum/mil Force (lbs/mil) 8 8.9 — — — — BreakEnergy (in-lbs) 21.18 19.21 — — — — Break Energy/mil (in-lbs/mil) 21.1819.21 — — — — Gauge Mic (mils) Average 1.00 1.00 0.99 0.97 0.99 0.97 Low0.93 0.93 0.92 0.90 0.94 0.92 High 1.08 1.11 1.05 1.01 1.03 1.04

The maximum rate is controlled in part by the “bubble stability” of theforming film. When the line speed/extrusion rate is over the maximumrate, the bubble formed by the film being blown by air becomes unstable.The bubble stability is related two main factors:

-   -   3. Melt strength of the polymer blend: higher the melt strength,        higher the maximum rate. The addition of small amount of the        diene terpolymer (DTP) enhances the melt strength of the base        polyethylene significantly. Hence the DTP blend have higher        maximum rate than the base polyethylene (Exceed 1018).    -   4. Cooling capability of the line: higher cooling capability,        higher the maximum rate. The Line I line has higher cooling        capability than Line II.

Typically, the Maximum Die Rate is used to normalize the extrusion rate.For the Line II, the Maximum Die Rate for 1 wt % DTP or 5 wt % LD wasabout 13 to 13.5 lb/in-hr. On the Line I, these same blends can beformed at a Maximum Die Rate of at least 18 to 20 lbs/in-hr.

In FIGS. 2 and 3, each symbol, whether filled or open, represents thesame composition. In FIGS. 2 and 3, the filled black symbols representthe use of a traditional, prior art cooling device positioned againstthe die, wherein the open symbols represent the inventive process ofhaving the cooling device a distance from the die of 14 inches (seeTable 2). FIG. 2 illustrates the film MD-Elmendorf tear as a function offilm microstructure parameters: Herman's orientation function (lamellar)percent crystallinity and inter lamellar spacing; while FIG. 3 elucidatethe film stiffness measure by 1% MD secant as a function of the abovementioned three parameters. In FIG. 3, the open diamond refers to “1%DTP (1,7), as it does in FIG. 2, and “+” inside box or alone is meant tobe 10% Enable 2005 at 18-20 lb/in-hr, as it is in FIG. 2. Thecrystallinity data and inter lamellar spacing data (y-axis) are in FIGS.4 and 5 as bar graphs for illustrative purposes.

Now, having described the various features of the inventive process andfinished films resulting therefrom, described here in numberedparagraphs is:

-   P1. A method of forming a finished film comprising (or consisting    essentially of, or consisting of):    -   extruding a molten polyethylene comprising a diene terpolymer        modifier through a die opening to form a film, wherein the        diene-terpolymer modifier is a terpolymer comprising        ethylene-derived units, C₃ to C₁₀ α-olefin derived units, and        diene-derived units;    -   causing the film to progress in a direction away from the die        opening;    -   cooling the film at a distance from the die opening, the        distance adjusted to effect the properties of the film; and        isolating a finished film therefrom.-   P2. The method of numbered paragraph 1, wherein the resulting    finished film meets the following relationship:

ETMD+0.103f _(H)·χΔ>200 (g/mil); or

ETMD+0.103f _(H)·χΔ>240 (g/mil); or

ETMD+0.103f _(H)·χΔ>280 (g/mil); and,

SCMD−2.62f _(H)·χΔ>21,000 (psi); or

SCMD−2.62f _(H)·χΔ>22,000 (psi); or

SCMD−2.62f _(H)·χΔ>23,000 (psi);

-   -   wherein “ETMD” is MD Elmendorf tear (g/mil); SCMD is the MD 1%        Secant (psi); f_(H) is the Herman Orientation Function        (lamella); χ is percent crystallinity; and Δ is inter-lamellar        spacing (Δ).

-   P3. The method of numbered paragraphs 1 or 2, wherein the    polyethylene is a linear low density polyethylene having a density    within the range from 0.850 g/cm³ to 0.930 g/cm³. And wherein the    polyethylene is a linear low density polyethylene having a melt    index (190/2.16) within the range from 0.40 or 0.60 or 0.80 g/10 min    to 1.20 or 1.40 or 1.60 or 2.00 or 4.00 g/10 min.

-   P4. The method of any one of the previous numbered paragraphs,    wherein the polyethylene also comprises within the range from 0.10    wt % to 10 wt % of a diene-terpolymer modifier.

-   P5. The method of numbered paragraph 4, wherein the diene-terpolymer    modifier is a terpolymer comprising ethylene-derived units, C₃ to    C₁₀ α-olefin derived units, and diene-derived units; wherein the    diene is preferably an alpha-omega linear diene.

-   P6. The method of numbered paragraph 5, wherein the diene terpolymer    comprises ethylene-derived units and within a range from 0.01 wt %    to 10.0 wt % diene derived units, and 1.0 wt % to 20 wt % of C₄ to    Co₁₀ α-olefin derived units based on the weight of the diene    terpolymer, wherein the diene terpolymer has:    -   a) a g′_(vis) of less than 0.90;    -   b) an M_(w) within a range of from 70,000 g/mol to 300,000        g/mol;    -   c) an M_(w)/M_(n) within the range of from 3.0 to 12; and    -   d) an Mz/M_(n) of greater than 14.0.

-   P7. The method of any one of the previous numbered paragraphs,    wherein the distance is within a range of from 1, or 2, or 4, or 8    cm to 50 cm, or 60 cm, or 80 cm, or 3 meters.

-   P8. The method of any one of the previous numbered paragraphs,    wherein the cooling is provided by air blown on at least a portion    of the film, preferably around the complete circumference of the    film when blown into a hollow tube, the temperature of the air at    least 10° C. cooler than the surrounding temperature. Preferably,    the cooling air is at a temperature within the range from 5 or    10° C. to 15 or 20 or 25° C.; and preferably the surrounding    temperature is within a range from 20 or 30° C. to 50 or 60° C.

-   P9. The method of any one of the previous numbered paragraphs,    wherein the film is formed at a Maximum Die Rate within a range from    13, or 15, or 18, or 22 lb/in-hr to 26 or 30 or 40 lb/in-hr.

-   P10. The method of any one of the previous numbered paragraphs,    wherein the film is formed at a Maximum Rate within a range from 350    lb/hr to 500 lb/hr.

-   P11. The method of numbered paragraph 4, wherein the MD Tensile    Strength of the finished film is within a range from 8000 psi (55    MPa) to 16,000 psi (110 MPa).

-   P12. The method of numbered paragraph 4, wherein the MD Elongation    of the finished film is within a range from 480% to 680%.

-   P13. The method of numbered paragraph 4, wherein the Haze (ASTM    D1003) of the finished film is less than 6 or 4%.

-   P14. The method of any one of the previous numbered paragraphs,    wherein the die opening is in the form of a ring and the molten    polyethylene emanating therefrom is in the form of a continuous    tube.

-   P15. The method of any one of the previous numbered paragraphs,    wherein the finished film has a thickness within the range from 10    or 15 m to 50 or 75 or 100 m.

-   P16. The method of any one of the previous numbered paragraphs,    wherein the distance is the ratio of H/D and is a value within a    range from 0.1 or 0.5 or 1 to 2 or 3 or 4 or 5.

-   P17. A polyethylene blown film having a MD Tensile Strength of the    finished film is within a range from 6000 psi (41 MPa) to 16,000 psi    (110 MPa) comprising (or consisting essentially of, or consisting    of):    -   a linear low density polyethylene having a density within the        range from 0.850 g/cm³ to 0.930 g/cm³ and within the range from        0.10 wt % to 10 wt % of a diene-terpolymer modifier;    -   wherein the diene terpolymer modifier comprises ethylene-derived        units and within a range from 0.01 wt % to 10.0 wt % diene        derived units, and 1.0 wt % to 20 wt % of C₄ to C₁₀ α-olefin        derived units based on the weight of the diene terpolymer,        wherein the diene terpolymer has:        -   a) a g′_(vis) of less than 0.90;        -   b) an M_(w) within a range of from 70,000 g/mol to 300,000            g/mol;        -   c) an M_(w)/Mn within the range of from 3.0 to 12; and        -   d) an M_(z)/M_(n) of greater than 14.0.

-   P18. The polyethylene blown film of numbered paragraph 17, achieved    at a Maximum Die Rate within a range from 13, or 15, or 18, or 22    lb/in-hr to 26 or 30 or 40 lb/in-hr.

-   P19. The polyethylene blown film of numbered paragraph 17 or 18,    wherein the diene is selected from 5-vinyl-2-norbornene,    1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene,    1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene,    1,12-tridecadiene, and 1,13-tetradecadiene derived units.

-   P20. The polyethylene blown film of any one of numbered paragraphs    17-19, wherein the linear low density polyethylene has a melt index    (190/2.16) within the range from 0.20 g/10 min to 10.0 g/10 min.

-   P21. The polyethylene blown film of any one of numbered paragraphs    17-20, wherein the linear low density polyethylene has a g′_(vis) of    greater than 0.90.

Also disclosed herein is the use of a blown film line to form a finishedfilm by extruding a molten polyethylene comprising a diene terpolymermodifier through a die opening to form a film, wherein thediene-terpolymer modifier is a terpolymer comprising ethylene-derivedunits, C₃ to C₁₀ α-olefin derived units, and diene-derived units;causing the film to progress in a direction away from the die opening;cooling the molten polyethylene in the form of a film at a distance fromthe die opening, the distance adjusted to allow relaxation of the moltenpolyethylene prior to solidification and/or crystallization uponcooling; and isolating a finished film therefrom. The polyethylene maybe characterized by any one or combination of features described herein.

The phrase “consisting essentially of” in a film means that no otheradditives (additional polymers and/or antioxidants, antistatic agents,antislip agents, fillers) are present in the composition being referredto other than those named, or, if present, are present to a level nogreater than 0.5, or 1.0, or 2.0, or 4.0 wt % by weight of thecomposition; and in a process, “consisting essentially of” means that noother major process step is present or effects the claimed filmproperties such that the value would be outside the claim scope.

For all jurisdictions in which the doctrine of “incorporation byreference” applies, all of the test methods, patent publications,patents and reference articles are hereby incorporated by referenceeither in their entirety or for the relevant portion for which they arereferenced, including the priority document(s).

1. A method of forming a finished film comprising: extruding a moltenpolyethylene comprising a diene terpolymer modifier through a dieopening to form a film, wherein the diene-terpolymer modifier is aterpolymer comprising ethylene-derived units, C₃ to C₁₀ α-olefin derivedunits, and diene-derived units; causing the film to progress in adirection away from the die opening; cooling the film at a distance fromthe die opening, the distance adjusted to effect the properties of thefilm; and isolating a finished film therefrom.
 2. The method of claim 1,wherein the resulting finished film meets the following relationship:ETMD+0.103f _(H)·χΔ>200 (g/mil); andSCMD−2.62f _(H)·χΔ>21,000 (psi); wherein “ETMD” is MD Elmendorf tear(g/mil); “SCMD” is the MD 1% Secant (psi); f_(H) is the HermanOrientation Function (lamella); χ is percent crystallinity; and Δ isinter-lamellar spacing (Å).
 3. The method of claim 1, wherein thepolyethylene is a linear low density polyethylene having a densitywithin the range from 0.850 g/cm³ to 0.930 g/cm³.
 4. The method of claim1, wherein the diene terpolymer modifier is present within the rangefrom 0.10 wt % to 10 wt % of a diene-terpolymer modifier.
 5. The methodof claim 1, wherein the diene is an alpha-omega linear diene.
 6. Themethod of claim 1, wherein the diene terpolymer comprises within a rangefrom 0.01 wt % to 10.0 wt % diene derived units, and 1.0 wt % to 20 wt %of C₄ to C₁₀ α-olefin derived units based on the weight of the dieneterpolymer, wherein the diene terpolymer has: a) a g′_(vis) of less than0.90; b) an M_(w) within a range of from 70,000 g/mol to 300,000 g/mol;c) an M_(w)/M_(n) within the range of from 3.0 to 12; and d) anM_(z)/M_(n) of greater than 14.0.
 7. The method of claim 1, wherein thedistance is within a range of from 1 cm to 3 meters.
 8. The method ofclaim 1, wherein the cooling is provided by air blown on at least aportion of the film, the temperature of the air at least 10° C. coolerthan the surrounding temperature.
 9. The method of claim 1, wherein thefilm is formed at a Maximum Die Rate of at least 13 lb/in-hr.
 10. Themethod of claim 1, wherein extrusion takes place at a Maximum Ratewithin a range from 350 lb/hr (159 kg/hr) to 500 lb/hr (227 kg/hr). 11.The method of claim 1, wherein the MD Tensile Strength of the finishedfilm is within a range from 6000 psi (41 MPa) to 16,000 psi (110 MPa).12. The method of claim 1, wherein the MD Elongation of the finishedfilm is within a range from 480% to 680%.
 13. The method of claim 1,wherein the Haze (ASTM D1003) of the finished film is less than 6 or 4%.14. The method of claim 1, wherein the die opening is in the form of aring and the molten polyethylene emanating therefrom is in the form of acontinuous tube.
 15. The method of claim 1, wherein the finished filmhas a thickness within the range from 10 or 15 am to 100 μm.
 16. Apolyethylene blown film having a MD Tensile Strength of the finishedfilm is within a range from 6000 psi (41 MPa) to 16,000 psi (110 MPa)comprising: a linear low density polyethylene having a density withinthe range from 0.850 g/cm³ to 0.930 g/cm³ and within the range from 0.10wt % to 10 wt % of a diene-terpolymer modifier; wherein the dieneterpolymer modifier comprises ethylene-derived units and within a rangefrom 0.01 wt % to 10.0 wt % diene derived units, and 1.0 wt % to 20 wt %of C₄ to Co₁₀ α-olefin derived units based on the weight of the dieneterpolymer, wherein the diene terpolymer has: a) a g′_(vis) of less than0.90; b) an M_(w) within a range of from 70,000 g/mol to 300,000 g/mol;c) an M_(w)/M_(n) within the range of from 3.0 to 12; and d) anM_(z)/M_(n) of greater than 14.0.
 17. The polyethylene blown film ofclaim 16, achieved at a Maximum Die Rate of at least 13 lb/in-hr. 18.The polyethylene blown film of claim 16, wherein the diene is selectedfrom 5-vinyl-2-norbornene, 1,4-pentadiene, 1,5-hexadiene,1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene,1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, and1,13-tetradecadiene derived units.
 19. The polyethylene blown film ofclaim 16, wherein the linear low density polyethylene has a melt index(ASTM D 1238 190° C., 2.16 kg) within the range from 0.20 g/10 min to10.0 g/10 min.
 20. The polyethylene blown film of claim 16, wherein thelinear low density polyethylene has a g′_(vis) of greater than 0.90.